FAST PYROLYSIS OF LEUCAENA LEUCOCEPHALA IN A CIRCULATING FLUIDISED BED REACTOR

摘要

A fast-growing mimosoid tree, Leucaena leucocepphala has been promoted as an energy crops inrnThailand. Its woody biomass contained 2wt% ash and had a lower heating value (LHV) of 17 MJ/kg. It was fastrnpyrolysed in a bench-scale circulating fluidised bed (CFB) reactor at 450-550℃. The effect of reaction temperaturernon product yields and properties was investigated. The pyrolysis products are bio-oil, char and gas. The bio-oil yieldsrnwere monitored by two means (1) heavy and light fractions and (2) organic and reactor water. The bio-oil propertiesrntested included water content, pH, viscosity and higher heating value. The results show that almost 69 wt% of totalrnbio-oil was produced at a controlled pyrolysis temperature of 500℃. This bio-oil yield can be separated into 55 wt%rnheavy and 14 wt% light fractions or 46 wt% organics and 23 wt% reaction water. According to the bio-oil analysis, itrnwas found that the heavy bio-oils contained low water content (12-20 wt%), whereas the light ones containedrnsignificantly higher water content (76-89 wt%). The pH values of heavy and light bio-oils were slightly different inrnthe range of 2.6-3.3. The heavy bio-oil had a viscosity measured at 40℃ of 27-56 cSt and the higher heating valuern(HHV) of 20-23 MJ/kg (wet basis), 24-26 MJ/kg (dry basis). Statistical analysis shows that the pyrolysis temperaturernled to the reduction of char yield, the increase of gas yield as well as the increase of the HHV and viscosity of thernheavy bio-oil.